JP4556784B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure sensor formed by joining a pedestal having a pressure introduction hole to a semiconductor diaphragm type sensor chip, and more particularly to a pressure sensor in which the pressure introduction hole is sealed with a protective gel member.

  Conventionally, as this type of pressure sensor, for example, those described in Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4 and the like have been proposed.

  This has a concave portion formed on the back surface, and a thin portion on the surface side corresponding to the concave portion is configured as a diaphragm, and a semiconductor diaphragm type sensor chip having a piezoresistor on the front surface and the back surface of the sensor chip are joined. And a pedestal made of glass or the like having a through hole that leads from the recess to the diaphragm.

  Here, the semiconductor diaphragm type sensor chip is bonded to the pedestal by anodic bonding or the like, and the gel member that protects the sensor chip, particularly the back surface of the diaphragm of the sensor chip, in the through hole of the pedestal and the recess of the sensor chip. Is filled.

  Such a pressure sensor is configured as a so-called “diaphragm back surface-sealed pressure sensor”. In this pressure sensor, pressure is introduced from the through hole of the pedestal through the gel member to the diaphragm, and from the sensor chip. A signal corresponding to the pressure applied by the piezoresistive effect is output.

  Here, this type of pressure sensor is applied, for example, when measuring the pressure of a pressure medium such as a corrosive liquid or gas, and in order to protect the sensor chip from such a corrosive pressure medium, As described above, the gel member protects it.

  The gel member is also injected to prevent the intrusion of moisture from the through hole of the pedestal into the diaphragm of the sensor chip and the destruction of the diaphragm when the invading water freezes at low temperatures and expands in volume. Has been.

Specifically, such a pressure sensor measures a differential pressure before and after a DPF (diesel particulate filter) as an exhaust purification filter provided in an exhaust pipe of a diesel engine vehicle, or a pressure in an EGR atmosphere. It is applied to a sensor for measuring
JP-A-4-370726 Japanese Patent Laid-Open No. 5-133828 JP-A-11-201845 JP 2002-221462 A

  By the way, in recent years, pressure sensors that can operate in a wide temperature range from a low temperature of 0 ° C. or lower to a high temperature of 100 ° C. or higher, such as automobile sensors, have been demanded.

  According to the study of the present inventor, in this type of pressure sensor, the gel member becomes hard at a low temperature, for example, −30 ° C. or lower, and the distortion of the piezoresistor that is the gauge portion changes from the diaphragm back surface due to the deformation stress. Therefore, it was found that the sensor output characteristics at the low temperature fluctuate.

  However, conventionally, no countermeasure has been taken for such a change in sensor characteristics at low temperatures due to the deformation of the gel member.

  The present invention has been made in view of the above problems, and aims to suppress fluctuations in sensor characteristics at low temperatures due to deformation of a gel member that seals the back surface of the diaphragm in a diaphragm back surface pressure sensor. To do.

  Here, as a result of intensive studies on the behavior of the gel member filled in the through hole of the pedestal at a low temperature, the present inventor has come to consider the following mechanism.

  If the diameter L of the through hole in the pedestal is large, even if the gel member is deformed hard at low temperatures, the gel member can move in the wide through hole in the opposite direction to the diaphragm, and the stress of the gel member can be relieved. Displacement on the back of the diaphragm is suppressed.

  However, when the diameter L of the through hole is small and the length of the through hole, that is, the thickness T of the pedestal is large, the through hole becomes long and the displacement of the gel member in the above direction is limited. For this reason, the stress relaxation of the gel member described above becomes insufficient, and conversely, the deformation stress of the gel member is applied to the rear surface of the diaphragm, thereby displacing the rear surface of the diaphragm. The present inventor has thus considered that the gel member ensures its own shape stability.

Therefore, the present inventor has be added to improve the relationship between the diameter L and the thickness T of the base of the through holes in the base, believed that it would be good, we found the present invention.

In order to achieve the above object, the present invention joins a semiconductor diaphragm type sensor chip (10) to a pedestal (20) having a through hole (21) leading to the back side of the diaphragm (14). ) Ri Na sealed by a gel member (30), the diameter of the base (the sensor chip (10) side of the opening in the through hole (21) of 20) (21a), the recess in the sensor chip (10) In the pressure sensor of the diaphragm back surface sealing type that is smaller than the diameter of (13), a portion of the pedestal (20) opposite to the sensor chip (10) is supported by the case (40). (40) is provided with a hole (41) that communicates with the through hole (21) and introduces pressure, and the hole (41) has a gel continuously from the through hole (21). Member (30) is full The diameter L1 on the through hole (21) side of the hole (41) of the case (40) is larger than the diameter L of the through hole (21) of the pedestal (20), and the case (40) The diameter L2 on the pressure introduction side in the hole (41) of the case (40) is larger than the diameter L1 on the through hole (21) side in the hole (41). the thickness of the) T is smaller than the diameter L of the pedestal (20) through hole (21) and feature.

According thereto, it is possible to suppress variations in sensor characteristics at low temperatures due to the deformation of the gel member for sealing the dust diaphragm and the back surface.

Further, in the present invention, the opening of the sensor chip (10) side of the transmembrane throughbore (21) the diameter of (21a), is set to be smaller than the diameter of the recess (13) in the sensor chip (10).

  According to this, since the area excluding the through hole (21) on the surface on the sensor chip (21) side of the pedestal (20) can be taken widely, the size of the pressure sensor is considered in a limited size. The bonding area between the pedestal (20) and the sensor chip (10) can be sufficiently secured, and the strength of the bonded structure can be sufficiently secured.

In the present invention , the portion of the pedestal (20) opposite to the sensor chip (10) is supported by the case (40), and the case (40) communicates with the through hole (21). A hole (41) for introducing the pressure is provided. The hole (41) is continuously filled with the gel member (30) from the through hole (21). ), it is assumed that the diameter L1 of the through hole (21) side of the hole (41) is configured as a large hole than the diameter L of the through hole (21).

  Thus, when the pedestal (20) is supported by the case (40), by providing the hole (41) in the case (40), the through hole (21 of the pedestal (20) is formed from the hole (41). ) To introduce pressure into the sensor chip (10).

  Further, by filling the hole (41) of the case (40) with the gel member (30), the sensor chip (10) is also protected in this portion, but the hole (41) of the case (40) is also provided. Since the diameter L1 on the through hole (21) side in the hole (41) is larger than the diameter L of the through hole (21), stress relaxation of the gel member (30) at low temperature is achieved. It can be done more appropriately.

Further, in the present invention, the hole (41), than the diameter L1 of the through hole (21) side of the hole (41) that is configured as a hole a larger diameter L2 of the pressure introduction side.

  According to that, since the hole (41) of the case (40) can be formed into a hole shape whose diameter is increased to the opposite side of the diaphragm (14), the gel member (30) filled in the hole (41) The inside of the hole (41) can be easily moved in the opposite direction to the diaphragm (14), and the stress of the gel member (30) at a low temperature can be relieved in the hole (41) of the case (40). .

  In addition, in the hole (41) of the case (40), on the pressure introduction side, the intrusion of moisture can be suppressed by the gel member (30) having a larger capacity. It can be surely suppressed.

  Here, the base (20) in the pressure sensor of the present invention can be made of glass, and the gel member (30) is made of fluorine gel, silicone gel, or fluorosilicone gel. Can be what you have.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
The pressure sensor according to the present embodiment is applied, for example, when measuring the pressure of a pressure medium such as a corrosive liquid or gas. Specifically, the pressure sensor measures exhaust gas in an exhaust pipe of a diesel engine vehicle. The present invention is applied to a sensor or the like that measures a differential pressure before and after a DPF (diesel particulate filter) as an exhaust purification filter provided in the exhaust pipe, or measures a pressure in an EGR atmosphere.

  FIG. 1 is a diagram showing a schematic cross-sectional configuration of a diaphragm back surface sealed pressure sensor 100 as a piezo-type pressure sensor device according to an embodiment of the present invention.

  As shown in FIG. 1, the pressure sensor 100 of the present embodiment is roughly composed of a semiconductor diaphragm type sensor chip 10 and a pedestal 20 having a through hole 21 as a pressure introduction hole joined to the sensor chip 10. The gel member 30 filled in the through hole 21 is provided.

  The sensor chip 10 is made of a semiconductor substrate such as a silicon semiconductor substrate, and a recess 13 formed by chemical etching or the like is formed on the back surface 12 thereof. In the sensor chip 10, a thin portion on the surface 11 side corresponding to the recess 13 is configured as a diaphragm 14.

  Further, on the surface 11 of the sensor chip 10, a piezoresistor 15 made of a diffused resistor or the like is provided in the diaphragm 14 portion. A plurality of the piezoresistors 15 are provided and constitute a bridge circuit as shown in FIG. Thus, the sensor chip 10 of the present embodiment is configured as a semiconductor diaphragm type sensor chip.

  And in the sensor chip 10, the signal according to the pressure applied by the piezoresistive effect is output.

  Specifically, the diaphragm 14 receives pressure, the diaphragm 14 is distorted by the pressure, and the bridge circuit formed in the diaphragm 14 responds to a signal based on the distortion of the diaphragm 14, that is, an applied pressure value. Level signals are output.

  In the present embodiment, the sensor chip 10 is fixed to the pedestal 20 on the back surface 12 side at the peripheral portion of the diaphragm 14, that is, the thick portion 16. In this example, the base 20 is made of glass, and is joined to the sensor chip 10 made of a silicon semiconductor by anodic bonding.

  Here, in the base 20 joined to the back surface 12 of the sensor chip 10, the through hole 21 as a pressure introduction hole is configured as a hole penetrating from the surface on the sensor chip 10 side to the surface on the opposite side. The through-hole 21 has a straight round hole shape as in a general case.

  The sensor chip 20 is arranged with the diaphragm 14 facing the through hole 21 of the base 20 on the back surface 12 side. That is, the through hole 21 of the pedestal 20 communicates from the recess 13 of the sensor chip 10 to the diaphragm 14.

  Here, in the pressure sensor 100 of the present embodiment, the ratio L / T between the diameter L of the through hole 21 in the base 20 and the thickness T of the base 20 is 1 <L / T <3. Thus, the grounds for adopting a configuration in which the ratio L / T is in the range of greater than 1 and less than 3 in this embodiment will be described later.

  Further, in the present embodiment, the diameter of the opening 21 a on the sensor chip 10 side in the through hole 21 of the base 20 is smaller than the diameter of the recess 13 in the sensor chip 10. Therefore, as shown in FIG. 1, the pedestal 20 has a shoulder portion 22 that protrudes inside the recess 13 of the sensor chip 10.

  The through hole 21 of the pedestal 20 can be created by adopting a processing method such as cutting or sandblasting using ultrasonic vibration.

  The pedestal 20 is a flat rectangular pedestal corresponding to, for example, a generally rectangular plate-shaped sensor chip 10, and the diameter L of the through hole 21 is, for example, 0.8 mm to 0.8 mm after satisfying the range of the above ratio L / T. The thickness T of the base 20 can be about 0.7 mm to 2.1 mm, for example, about 2.1 mm.

  Here, as shown in FIG. 1, the piezoresistor 15 of the sensor chip 10 is provided at a portion where the distortion of the diaphragm 14 is large, in the illustrated example, at the periphery of the diaphragm 14 in order to increase sensitivity. Further, the piezoresistor 15 is located inside the diameter of the opening 21 a on the sensor chip 10 side in the through hole 21 of the base 20.

  The through hole 21 of the pedestal 20 and the recess 13 of the sensor chip 10 are filled with a gel member 30, and the gel member 30 seals and protects the back surface of the sensor chip 10, particularly the diaphragm 14. .

  As this gel member 30, for example, a gel material such as a silicone gel, a fluorine-based gel, or a fluorosilicone gel can be used. By injecting and curing such a gel material into the through hole 21, the gel member 30. Is filled.

  As described above, the present pressure sensor 100 is applied when measuring the pressure of a pressure medium such as corrosive liquid or gas such as exhaust gas pressure of a diesel engine. In order to protect the sensor chip 10, particularly the back surface of the diaphragm 14, from the pressure medium, protection by the gel member 30 is made.

  Moreover, the pressure sensor 100 of this embodiment has the case 40 attached to the appropriate place of the exhaust system of a vehicle, as FIG. 1 shows. The case 40 has a terminal (not shown) that can be electrically connected to the outside.

  For example, the case 40 is made of a resin such as PBT (polybutylene terephthalate) or PPS (polyphenylene sulfide), and further, a terminal such as a terminal made of Cu or 42 alloy is insert-molded. Can be adopted.

  The sensor chip 10 is bonded and fixed to the case 40 with an adhesive 50 via a base 20 integrated therewith. As such an adhesive 50, for example, an adhesive made of a resin that exhibits an adhesive function when applied and cured, specifically, a silicone-based adhesive or a fluorosilicone-based adhesive may be employed. it can.

  Further, the terminals of the case 40 and the sensor chip 10 are electrically connected by a bonding wire made of gold or aluminum (not shown). Thereby, electrical exchange between the sensor chip 10 and the outside becomes possible.

  Here, the portion of the pedestal 20 opposite to the sensor chip 10 is supported by the case 40, but the case 40 communicates with the through hole 21 of the pedestal 20 and also has a hole 41 for introducing pressure. Is provided. The hole 41 is filled with the gel member 30 continuously from the through hole 21.

  The hole 41 of the case 40 is, for example, a round hole. In this embodiment, the hole 41 has a diameter L1 on the through hole 21 side of the hole 41 larger than the diameter L of the through hole 21. Configured as a hole.

  Furthermore, the hole 41 is configured as a hole having a diameter L2 on the pressure introduction side larger than the diameter L1 on the through hole 21 side in the hole 41. In this example, the hole 41 has a hole shape whose diameter is increased in a tapered shape on the side opposite to the diaphragm 14, that is, on the pressure introduction side.

  In the pressure sensor 100, pressure is introduced from the hole 41 of the case 40 and the through hole 21 of the base 20 through the gel member 30 to the back surface 12 of the sensor chip 10, that is, the back surface 12 of the diaphragm 14. From, the signal according to the applied pressure is output by the above-mentioned piezoresistance effect. A specific detection method will be described later.

  Next, a method for manufacturing the pressure sensor 100 of the present embodiment will be described with reference to FIGS. 2 (a) to 2 (d) and FIGS. 3 (a) to 3 (d) are process diagrams showing this manufacturing method in a schematic cross section of a work, and mainly show a manufacturing method of the sensor chip 10. .

  An example of a more specific cross-sectional configuration of the sensor chip 10 in the pressure sensor 100 is shown in FIGS.

In the example shown in FIGS. 3C and 3D, the sensor chip 10 includes a P-type layer (PSub layer) 201, an N ⁻ layer as a P-type silicon substrate from the back surface 12 side to the front surface 11 side. (N-type epitaxial layer) 203 is composed of a silicon semiconductor substrate 200 laminated, and the N ⁻ layer 203 has a piezoresistive 15 formation region through a P-type region having an impurity concentration different from that of the P-type layer 201. It is separated from the surrounding area, and the isolation 204 is secured.

The piezoresistor 15 is formed in the N ⁻ layer as a P-type region. In practice, at least four piezoresistors 15 are formed, and constitute a bridge circuit (see FIG. 4) described later.

  Further, the upper surface of the silicon semiconductor substrate 200, that is, the surface 11 side of the sensor chip body is covered with an oxide film 17, and a wiring 18 made of an Al thin film is formed on the oxide film 17. The piezoresistors 15 are connected to each other through contact holes formed in the wiring 18 and the oxide film 17.

  A protective film 19 made of a silicon oxide film, a silicon nitride film, or the like is formed on the oxide film 17 excluding the wiring 18 to protect the sensor chip 10. The sensor chip 10 can be manufactured using a known semiconductor manufacturing technique. Next, an example of the manufacturing method will be described with reference to FIGS.

First, as shown in FIG. 2A, a P-type layer 202 having a different impurity concentration is formed in a predetermined region on one surface side of a P-type silicon substrate 201 by ion implantation or the like. On the side, an N ⁻ layer 203 is grown and formed in an impurity atmosphere such as phosphorus (P).

Next, as shown in FIG. 2B, boron (B) ions or the like are implanted from the surface of the N ⁻ layer 203 and diffused, and the P-type layer 202 having a different impurity concentration is formed on the N ⁻ layer 203. By diffusing to the surface side, the P-type layer 201 as the P-type silicon substrate and the N ⁻ layer 203 are laminated and the silicon semiconductor substrate 200 in which the isolation 204 is formed is formed.

Next, as shown in FIG. 2C, an oxide film 17 is formed on the upper surface of the silicon semiconductor substrate 200 by a method such as sputtering, vapor deposition, or heat treatment, and the N ⁻ layer is formed by the oxide film 17. 203 and isolation 204 are coated.

  Next, as shown in FIG. 2D, a piezoresistor 15 is formed on the surface of the silicon semiconductor substrate 200 by ion implantation or diffusion using boron (B) ions or the like through the oxide film 17.

  Next, as shown in FIG. 3A, a contact hole is formed in a desired portion of the oxide film 17 by using a photolithography method or the like, and a wiring 18 made of an Al thin film is formed thereon by a vapor deposition method or the like. Then, the wiring 18 and the piezoresistor 15 are made conductive.

  Next, as shown in FIG. 3B, a protective film 19 made of a silicon oxide film, a silicon nitride film or the like is formed by a CVD method or the like.

  Thereafter, a part of the lower surface side of the silicon semiconductor substrate 200 is removed by anisotropic etching using an etching solution such as KOH while the upper surface side of the silicon semiconductor substrate 200 is masked. As a result, as shown in FIG. 3C, the diaphragm 14 is formed as the recess 13 is formed, and the sensor chip 10 is completed.

  Then, as described above, the pedestal 20 provided with the tapered through hole 21 is prepared by a processing method such as cutting or sandblasting using ultrasonic vibration, and the pedestal 20 and the sensor chip 10 are anodically bonded.

  Thereby, as shown in FIG. 3D, the sensor chip 10 and the base 20 are integrated. Subsequently, the case 40 and the pedestal 20 are further bonded via the adhesive 50. And the gel member 30 is inject | poured into the hole 41 of the case 40, and the through-hole 21 of the base 40, and this is hardened by heating etc.

  In addition, as a pressure sensor that can be used for actual pressure measurement by performing a process of electrically connecting the sensor chip 10 and a terminal (not shown) of the case 40 by wire bonding or the like, the pressure sensor according to this embodiment can be used. The diaphragm back surface pressure sensor 100 is completed.

  Such a pressure sensor 100 includes, for example, a diaphragm 14 due to a differential pressure between a pressure applied to the diaphragm 14 from the front surface 11 side of the sensor chip 10 and a pressure applied to the diaphragm 14 from the back surface 12 side of the sensor chip 10. The relative pressure type pressure sensor that detects pressure based on the distortion of the diaphragm 14 can be obtained.

  Although not limited, specifically, such a pressure sensor 100 of the relative pressure detection type is attached to the exhaust system of the diesel engine described above via the case 40, for example, and measures the exhaust gas pressure thereof. It can be applied as a thing.

  In this case, in the present pressure sensor 100, for example, atmospheric pressure serving as a reference pressure is introduced to the front surface 11 side of the sensor chip 10, and the exhaust gas pressure is passed through the gel member 30 on the back surface 12 side of the sensor chip 10. It is introduced into the diaphragm 14.

  At this time, each pressure is received by the front surface and the back surface of the diaphragm 14 of the sensor chip 10, a differential pressure between these two surfaces is detected based on the distortion of the diaphragm 14, and a signal from the sensor chip 10 based on the piezoresistance effect is received. From the bonding wire or the like, it is outputted to the outside through the terminal.

  A more specific detection operation in the pressure sensor 100 will be described with reference to FIG. FIG. 4 shows a connection diagram of the bridge circuit constituted by the piezoresistor 15. A Wheatstone bridge is constituted by four piezoresistors 15 (15a, 15b, 15c, 15d).

  When the pressure is applied, the diaphragm 14 is distorted and deformed. At this time, when the DC constant voltage V is applied between the input terminals Ia and Ib of the Wheatstone bridge shown in FIG. 4, the deformation of the diaphragm 14 is piezo-electric. A voltage (sensor signal) Vout having a level corresponding to the detected pressure is output between the output terminals Pa and Pb, and appears as a change in resistance value of the resistors 15a to 15d.

  The sensor signal Vout is output to the outside as a signal from the sensor chip 10 based on the piezoresistance effect. In this way, the pressure sensor 100 detects the pressure.

  By the way, according to the present embodiment, the sensor chip 10 having the concave portion 13 formed on the back surface 12 and the thin portion on the front surface 11 side corresponding to the concave portion 13 is configured as the diaphragm 14 and having the piezoresistor 15 on the front surface 11. A pedestal 20 having a through hole 21 joined to the back surface 12 of the sensor chip 10 and communicating from the recess 13 to the diaphragm 14, and a gel member 30 filled in the through hole 21 and the recess 13 to protect the sensor chip 10 is provided. In the pressure sensor in which pressure is introduced from 21 to the diaphragm 14 via the gel member 30 and a signal corresponding to the pressure applied by the piezoresistive effect is output from the sensor chip 10, The ratio L / T between the diameter L of the hole 21 and the thickness T of the base 20 is 1 <L / T <3. Sensor 100 is provided.

  Such a pressure sensor 100 of the present embodiment is applicable as a pressure sensor that can operate in a wide temperature range from a low temperature of 0 ° C. or lower to a high temperature of 100 ° C. or higher. In particular, the ratio L / T is 1 By making the range larger than 3 and less than 3, it is possible to suppress fluctuations in sensor characteristics even at an extremely low temperature of about −30 ° C.

  A specific state of the suppression of fluctuations in sensor characteristics at this extremely low temperature is shown in FIG. FIG. 5 is a diagram showing a result of an experiment conducted by the inventor focusing on the ratio L / T regarding the relationship between the diameter L of the through hole in the pedestal and the thickness T of the pedestal. The ratio L / T and the low temperature are shown in FIG. It is a figure which shows the relationship with the fluctuation | variation of the sensor characteristic in.

  As shown in FIG. 5, the inventor changed the ratio L / T by changing the diameter of the through hole 21 of the pedestal 20 (in the drawing, the diameter of the hole) from φ0.8 mm to φ2.0 mm. Sensors were prepared as samples, and TCO fluctuation (unit:% FS) before and after injection was examined for each of these samples.

  Here, “TCO fluctuation before and after injection” indicates the magnitude of fluctuations in sensor characteristics at low temperatures in each sample before and after the gel member 30 is injected. .

  Specifically, the sensor signal Vout is measured at room temperature and −30 ° C. for each sample before injecting the gel member 30, and the variation of the measured value at −30 ° C. with respect to the measured value at room temperature is obtained. The sensor signal Vout is measured at room temperature and −30 ° C. for each sample after the gel member 30 is injected, and the variation is similarly obtained.

  For example, for each sample, assuming that the fluctuation before injection of the gel member is a% and the fluctuation after injection is (a + b)%, these differences b% are characteristic fluctuations at low temperature due to the gel member 30. Equivalent to. The difference b% is the “TCO fluctuation before and after injection” shown in FIG.

  As shown in FIG. 5, the TCO variation decreases as the ratio L / T increases. When the ratio L / T is 1 or less, the TCO fluctuation exceeds the practical level of 1.5% FS, but the ratio L / T is larger than 1 and the ratio L / T is less than 3 at the practical level. It was confirmed that a certain 1.5% FS or less was satisfied.

  If the ratio L / T is 1 or less, the through hole 21 of the pedestal 20 has an elongated shape that is insufficient to relieve the stress of the gel member 30. Therefore, fluctuations in sensor characteristics at low temperatures are not practical. It becomes an appropriate size.

  On the other hand, the thickness T of the pedestal 20 is about 0.7 mm as a lower limit in consideration of the stability of the pedestal 20 and the warp when the sensor chip 10 is joined, and the diameter L of the through hole 21 is the sensor chip. The upper limit is about 2.1 mm from the standpoint of securing the joint area with 10 and the mechanical strength of the pedestal 20 itself.

  In consideration of these things and the experimental data shown in FIG. 5, in the present embodiment, the upper limit of the ratio L / T is set to 2.1 / 0.3 = 3, that is, less than 3.

  Thus, by setting the ratio L / T to a range greater than 1 and less than 3, fluctuations in sensor characteristics at low temperatures due to deformation of the gel member 30 that seals the back surface of the diaphragm can be suppressed.

  Moreover, in the pressure sensor 100 of this embodiment, the diameter of the opening part 21a by the side of the sensor chip 10 in the through-hole 21 is one of the characteristics that it is smaller than the diameter of the recessed part 13 in the sensor chip 10.

  In this way, as shown in FIG. 1, the thick portions 16 other than the recesses 13 in the sensor chip 10 are all joined in contact with the pedestal 20 without overlapping the through holes 21. A sufficient bonding area with the sensor chip 10 can be ensured, and the rigid body characteristics in the bonded structure of the sensor chip 10 and the base 20 are appropriately maintained.

Except for this point, in the present embodiment, although it is a reference diagram, as shown in FIG. 6 as a first modified example, the opening on the sensor chip 10 side in the through hole 21 of the base 20 The diameter of 21 a may be larger than the diameter of the recess 13 in the sensor chip 10.

  Further, in the pressure sensor 100 of the present embodiment, a portion of the pedestal 20 opposite to the sensor chip 10 is supported by the case 40, and communicates with the through hole 21 and introduces pressure into the case 40. The hole 41 is provided continuously with the gel member 30 from the through hole 21. The hole 41 has a diameter L1 on the through hole 21 side of the hole 41. It is also one of the features that it is configured as a hole larger than the diameter L of the through hole 21.

  As described above, the hole 40 that communicates with the through hole 21 of the pedestal 20 and that can introduce pressure is provided in the case 40, and the gel member 30 is continuously filled in the hole 41 from the through hole 21, thereby providing a sensor chip. The pressure can be introduced to the sensor chip 10 through the hole 41 and the gel member 30 in the through hole 21 of the pedestal 20 while protecting the sensor 10.

  Further, since the diameter L1 on the through hole 21 side in the hole 41 of the case 40 is configured to be larger than the diameter L of the through hole 21, even if the gel member 30 is hard deformed at a low temperature, the gel member 30 The inside of the hole 41 on the relatively large case 40 side can be easily moved in the direction opposite to the diaphragm 14.

  That is, by doing in this way, in the region extending from the through hole 21 of the pedestal 20 to the hole 41 of the case 40, the stress of the gel member 30 at a low temperature can be relieved, so that the displacement on the rear surface of the diaphragm 14 can be easily suppressed. .

  Further, in the pressure sensor of the present embodiment, the hole 41 is also configured as a hole having a diameter L2 on the pressure introduction side larger than the diameter L1 on the through hole 21 side in the hole 41. One.

  The case 40 is relatively easy to process as compared to the pedestal 20, and it is possible to form a hole 41 in the case 40 having a hole shape whose diameter is increased toward the pressure introduction side by molding or cutting. Easy.

  According to this, as described above, in the hole 41 of the case 40, the stress of the gel member 30 at a low temperature can be relieved, and moisture is blocked by the gel member 30 having a larger area and a large capacity on the pressure introduction side. Therefore, fluctuations in sensor characteristics at low temperatures can be more reliably suppressed.

  Here, FIG. 7 is a schematic cross-sectional view showing a pressure sensor 110 as a second modified example of the present embodiment, and a part of the hole 41 of the case 40 having a hole shape whose diameter is expanded toward the pressure introduction side is partially deformed. It is a thing.

  In the example shown in FIG. 1, the hole 41 having a diameter L2 on the pressure introduction side larger than the diameter L1 on the through hole 21 side has a hole shape that is tapered toward the pressure introduction side. However, in the pressure sensor 110 shown in FIG. 7, the hole 41 has a stepped inner hole, thereby forming a hole shape having a stepped diameter. Also in this case, the same effect as that shown in FIG. 1 is obtained.

  In the example shown in FIG. 1, the case 40 is resin-molded. However, as in the example shown in FIG. 7, the case 40 is separated from the resin portion 40a and the resin portion 40a. It is good also as what was comprised with the pipe 40b which is a body member and comprises at least one part of the hole 41. FIG.

  The pipe 40b is made of, for example, ceramic such as mullite or alumina, or metal such as 42 alloy, and is integrally fixed to the resin portion 40a by insert molding or press fitting.

  Here, the pipe 40b is inserted and fixed in the opening portion on the through hole 21 side in the hole portion 41, and the inner diameter of the pipe 40b corresponds to the diameter L1 on the through hole 21 side in the hole portion 41. .

  Further, in the pressure sensor 100 of the present embodiment, as shown in FIGS. 1 and 7, the piezoresistor 15 is located inside the diameter of the opening 21 a on the sensor chip 10 side in the through hole 21 of the glass pedestal 20. It is also advantageous to be located.

  According to this, the piezoresistor 15 is located further inside than the shoulder portion 22 of the base 20 in the recess 13 of the sensor chip 10. Therefore, the gel member 30 enters the space of the concave portion 13 covered by the shoulder portion 22, that is, the space on the shoulder portion 22 in the concave portion 13, and expands due to heat or the like. There is an advantage that it becomes difficult to receive.

(Other embodiments)
In addition, in the said embodiment, although the base 20 was comprised with glass, as a material of the base 20, other than glass, Si, a ceramic, etc. can be used, for example.

  This is a limitation in view of the use of a pressure sensor under the influence of exhaust gas, and if the shape of the sensor chip or the pedestal can be maintained, a metal (such as 42 alloy) having a linear expansion coefficient suitable for silicon can be used. it can.

  Further, as the gel member 30, other than the above-described fluorine-based gel, silicone-based gel, and fluorosilicone-based gel, any material can be used as long as it functions sufficiently as a sensor chip protection member or a pressure transmission member.

  Moreover, in the said embodiment, although the hole part 41 of case 40 becomes a hole shape which the diameter of the pressure introduction side expanded, such a shape of the hole part 41 is the above-mentioned taper-shaped diameter-expanded shape. Or it is not restricted to the diameter-expanded shape with a level | step difference, For example, you may become the hole expanded in diameter by becoming the shape where the side surface of the hole curved. Furthermore, the hole 41 of the case 40 may have a straight hole shape.

  Further, in the above embodiment, the pressure sensor 100 has the case 40 and is attached to the member to be measured via the case 40 and is used for the measurement operation. However, the present invention is not limited to this. For example, the pedestal 20 may be directly attached to the member to be measured without having the case 40 for measurement.

  Moreover, in the pressure sensor of the said embodiment, when measuring the differential pressure before and behind DPF as an exhaust purification filter provided in the exhaust pipe of a diesel engine vehicle, for example, the exhaust gas pressure on the upstream side of the DPF is The exhaust gas pressure is introduced to the front surface 11 side and the downstream exhaust gas pressure is introduced to the back surface 12 side of the sensor chip 10. In such a case, the front surface 11 side of the sensor chip 10 is covered with a gel member (not shown). May be protected.

  In the above embodiment, the pressure sensor is a differential pressure detection type, that is, a relative pressure detection type pressure sensor. However, the surface side of the diaphragm in the sensor chip is a reference pressure such as a vacuum, and a gel member is interposed on the back side of the diaphragm. The present invention can also be applied to an absolute pressure sensor that receives a pressure to be measured.

  Further, as described above, the use of the pressure sensor of the present invention is not limited to the above-described sensor for detecting the exhaust pressure. For example, the pressure sensor of the present invention can be used for various applications such as atmospheric pressure, engine intake pressure, various equipment and container pressure.

It is a schematic sectional drawing of the pressure sensor which concerns on embodiment of this invention. It is process drawing which shows the manufacturing method of the sensor chip in the pressure sensor which concerns on the said embodiment. FIG. 3 is a process diagram illustrating a sensor chip manufacturing method following FIG. 2; It is a connection diagram of the bridge circuit comprised by the piezoresistor in the pressure sensor which concerns on the said embodiment. It is a figure which shows the relationship between ratio L / T and the fluctuation | variation of the sensor characteristic in low temperature. It is a schematic sectional drawing which shows the 1st modification as a reference drawing of the said embodiment. It is a schematic sectional drawing which shows the 2nd modification of the said embodiment.

Explanation of symbols

10 ... sensor chip, 11 ... front surface of the sensor chip, 12 ... back surface of the sensor chip,
13 ... recess of sensor chip, 14 ... diaphragm, 15 ... piezoresistor,
20 ... glass pedestal, 21 ... through hole in glass pedestal,
21a ... opening of sensor hole side of through hole, 30 ... gel member, 40 ... case,
41: Hole of the case.

Claims (1)

A recess (13) is formed on the back surface (12), and a thin portion on the front surface (11) side corresponding to the recess (13) is configured as a diaphragm (14), and a piezoresistive (15) is formed on the surface (11). A sensor chip (10) having:
A pedestal (20) having a through hole (21) joined to the back surface (12) of the sensor chip (10) from the recess (13) to the diaphragm (14);
A gel member (30) that fills the through hole (21) and the recess (13) and protects the sensor chip (10);
The diameter of the opening (21a) on the sensor chip (10) side in the through hole (21) of the base (20) is smaller than the diameter of the recess (13) in the sensor chip (10). Pressure is introduced from the through hole (21) to the diaphragm (14) through the gel member (30), and a signal corresponding to the pressure applied by the piezoresistance effect is output from the sensor chip (10). In the pressure sensor
A portion of the pedestal (20) opposite to the sensor chip (10) is supported by the case (40),
The case (40) is provided with a hole (41) for communicating with the through hole (21) and for introducing the pressure,
The hole (41) is continuously filled with the gel member (30) from the through hole (21),
The diameter L1 on the through hole (21) side of the hole (41) of the case (40) is larger than the diameter L of the through hole (21) of the base (20), and the case (40). The diameter L2 on the pressure introducing side in the hole (41) of the case (40) is larger than the diameter L1 on the through hole (21) side in the hole (41). And
Furthermore, the thickness T of the said base (20) is smaller than the diameter L of the said through hole (21) of the said base (20), The pressure sensor characterized by the above-mentioned .

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